/*
 * Unified UUID/GUID definition
 *
 * Copyright (C) 2009-2018 Intel Corp.
 *  Huang Ying <ying.huang@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/uuid.h>
#include <linux/random.h>

#include "backport.h"

// Backport
#define UUID_STRING_LEN 36

const u8 uuid_le_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
const u8 uuid_be_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};

/***************************************************************
 * Random UUID interface
 *
 * Used here for a Boot ID, but can be useful for other kernel
 * drivers.
 ***************************************************************/
/*
 * Generate random UUID
 */
void generate_random_uuid(unsigned char uuid[16])
{
    get_random_bytes(uuid, 16);
    /* Set UUID version to 4 --- truly random generation */
    uuid[6] = (uuid[6] & 0x0F) | 0x40;
    /* Set the UUID variant to DCE */
    uuid[8] = (uuid[8] & 0x3F) | 0x80;
}
static void __uuid_gen_common(__u8 b[16])
{
    prandom_bytes(b, 16);
    /* reversion 0b10 */
    b[8] = (b[8] & 0x3F) | 0x80;
}
void uuid_le_gen(uuid_le *lu)
{
    __uuid_gen_common(lu->b);
    /* version 4 : random generation */
    lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
}
void uuid_be_gen(uuid_be *bu)
{
    __uuid_gen_common(bu->b);
    /* version 4 : random generation */
    bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
}
/**
 * uuid_is_valid - checks if UUID string valid
 * @uuid:   UUID string to check
 *
 * Description:
 * It checks if the UUID string is following the format:
 *  xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
 * where x is a hex digit.
 *
 * Return: true if input is valid UUID string.
 */
bool uuid_is_valid(const char *uuid)
{
    unsigned int i;
    for (i = 0; i < UUID_STRING_LEN; i++) {
        if (i == 8 || i == 13 || i == 18 || i == 23) {
            if (uuid[i] != '-')
                return false;
        } else if (!isxdigit(uuid[i])) {
            return false;
        }
    }
    return true;
}
static int __uuid_to_bin(const char *uuid, __u8 b[16], const u8 ei[16])
{
    static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
    unsigned int i;
    if (!uuid_is_valid(uuid))
        return -EINVAL;
    for (i = 0; i < 16; i++) {
        int hi = hex_to_bin(uuid[si[i] + 0]);
        int lo = hex_to_bin(uuid[si[i] + 1]);
        b[ei[i]] = (hi << 4) | lo;
    }
    return 0;
}
int uuid_le_to_bin(const char *uuid, uuid_le *u)
{
    return __uuid_to_bin(uuid, u->b, uuid_le_index);
}
int uuid_be_to_bin(const char *uuid, uuid_be *u)
{
    return __uuid_to_bin(uuid, u->b, uuid_be_index);
}
